CAREER: Phase transformations in complex oxides for energy storage: operando x-ray nanovision

Cornell University, Ithaca NY

Investigators

Abstract

PART 1: NON-TECHNICAL SUMMARY The efficient use of intermittent wind and solar energy necessitates grid storage - a pressing need for the transition towards a sustainable future. Sodium-ion batteries emerged as promising candidates for economical energy storage: sodium is abundant, enables faster charge rates, and allows avoiding the use of precious materials. Despite these excellent prospects, structural degradation of crystalline sodium-ion cathodes during operation prevents further developments. A particular challenge is understanding these degradation mechanisms during battery charge or discharge, while the degradation takes place. This NSF CAREER award project, supported by the Solid State and Materials Chemistry program in the Division of Materials Research, seeks to understand degeneration in cathodes and find what makes a sodium-ion cathode material durable. The project uses advanced x-ray characterization, thereby allowing researchers to see processes inside of real operating batteries at the nanometer length-scale in real-time. Through advancing fundamental understanding this work has a societal impact by laying the foundation for the improved design of novel energy storage materials. The project further aims at fostering diversity in the field of materials science through creating and disseminating to elementary, middle and high school students hands-on experiments for experiencing the importance of periodicity, nanotechnology, and microscopy. PART 2: TECHNICAL SUMMARY Sodium-ion technology promises sustainable grid storage. However, the limited understanding and control of the prevalent phase transformations continue to limit the energy density, charge rates, and calendar life of available cathode materials. Due to the lack of available tools for observing how phases nucleate, coexist, and propagate inside the building blocks of the cathode during operation, one cannot establish fundamental structure-property relationships. The overall objective of this NSF CAREER award, supported by the Solid State and Materials Chemistry program in the Division of Materials Research, is the systematic operando characterization of mesoscale structural and chemical mechanisms underpinning phase transformations in nanocrystalline intercalating oxides. In particular, using operando Bragg coherent diffractive imaging the research team images how coexisting phases nucleate and grow inside individual nanoparticles. Laue microdiffraction is used for elucidating how structural phases and ions propagate through grain boundaries. Finally, operando resonant x-ray scattering allows collecting spectroscopic data of coexisting phases. Accomplishing the specific aims is expected to develop a fundamental understanding of phase transformations in sodium-ion cathodes and beyond, and ultimately accelerate the search for materials with higher energy density, faster charge/discharge rates, and longer calendar life. Excellence in education builds on two strategic axes: (1)Vertical integration of traditionally underrepresented minorities and fostering of diversity in the field of materials science using the natural appeal of colors in nature. The project develops hands-on experiments, which leverage the interplay between nanoscience and optics, resulting in colors in butterflies. Additionally, the PI and his students teach electrochemistry to elementary, middle and high school students. (2) Development of a curriculum on coherent x-ray techniques, the defining feature of novel x-ray sources. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.